New Hampshire's Changing Wintertime Climate: Impact on Forestry Practices

Over the past four decades wintertime temperatures in New England have risen more than 2 degrees Celsius. This has had a significant impact on winter recreation in the region. Here we examine the effect of New Hampshire's warming wintertime climate on the logging industry, a vital source of revenue in New Hampshire, particularly in the northern counties such as Coos and Grafton. Recent statements from the industry have indicated that warmer wintertime temperatures have reduced the number of days for which the road is frozen and able to support the weight of the logging trucks. To assess the magnitude of change in New Hampshire, we examined the change in number of frozen road days in 15 locations for the period December through March for the years 1970 to 2007. We applied a Freeze-Thaw formula, based on daily mean temperatures, to determine when the roads were frozen or thawed. By dividing the state into three regions based on latitude and taking the mean results of the 5 towns located in each region, we find that since 1970 the northern region has lost 9 frozen road days and the central region has lost 10 frozen road days. The southern region also shows a loss in frozen days but with a much weaker trend. We also performed a sensitivity analysis by calculating trends using start years from 1965 to 1975 and found that the original results were robust. The strongest individual town trend was found in Berlin, located in Coos County, having already lost 18 days since 1970. Using estimates from a prior study suggest that the cost of a 9 day reduction in frozen road days per winter represents a loss of more than one million dollars in stumpage fees per year. The results of this study suggest that the forestry industry may need to consider alternative methods for logging in the near future.